At the request of Wikipedia editors, a new feature is being added to MediaWiki. Long lists of references (created with <ref> tags; they are also called citations or footnotes at some wikis) will automatically be displayed in columns. The number of columns will be determined by the width of each reader's screen. This will improve accessibility and make it easier for most people to read the references, especially on narrow or very wide screens. Short lists of references will not be affected.

Use the normal <references /> tag on any page with many references to see this feature on any wiki where the feature has been enabled. If you do not want columns used on that page, then use this wikitext code instead: <references responsive="0" />.

The server-side software will change on the normal deployment train during the week of 14 March 2017. However, the effect will not normally be visible (except on MediaWiki.org where it is responsive by default[1]) until it is manually enabled for your particular wiki. WMF-hosted wikis that want this feature working locally can request a config change to enable it.

After the software is deployed, but before it is enabled on your wiki, you can manually invoke the feature on individual pages by using this wikitext code: <references responsive /> instead of the plain <references /> tag or a local template.

Some Wikipedias have been using local templates such as {{Reflist}} to create columns or add other formatting. These templates should be updated (or their use deprecated as redundant) before this change is manually enabled at your local wiki.

Consider defining the default behavior for the template as being the default behavior for the <references /> tag and deprecating or removing parameters that define a fixed number of columns, regardless of screen size.

<references responsive /> will automatically wrap the list in <div class="mw-references-wrap">. With the feature enabled by default, any list with more than 10 references will also get the class mw-references-columns. In this mode, the references list is automatically split over multiple columns based on the available space on the screen. E.g. on narrow screens 1 or 2 columns, on wider screens 2 or 3. Given that this happens automatically, it is no longer necessary for editors to manually enable/disable the columns mode of a template.

Remember also that other customisations for the references list are best applied directly to the ol.references CSS selector in your wikis' MediaWiki:Common.css. Many wikis customise the font-size this way, for example. (No need to manually code it through a template). In case a DIV wrapper is needed for certain styles, the .mw-references-wrap CSS selector will apply to all references lists produced by <references responsive /> regardless of whether the columns were dynamically activated.

For compatibility with fixed-column layout, you can have the reflist and refhead templates make sure responsive mode is turned off with responsive=0 when a fixed number of columns is specified. You may also want edit relevant layout rules in your wiki's MediaWiki:Common.css to only match ol.references elements without a wrapping .mw-references-wrap parent in order to avoid repeated definitions of multi-column layout. This can be done in the CSS using e.g. a direct descendant > operator.